Emile berlineb



(No Model,)

' E. BERLINER.

TELEPHONE TRANSMITTER. No. 351,569.- \PaJtented'Oot. 26, 1886.

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UNITED STATES PATENT Orrice.

i EMILE BERLINER, OF IVASHINGTON, DISTRICT OF COLUMBIA.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 351,569,dated October26, 1886.

To all whom it may concern:

Be it known that l, EMILE BERLINER, rcsiding at Washington, in theDistrict of Co lumbia, have invented certain Improvements inTelephone-Transmitters, of which the following is a specification. V

My invention relates to telephonic transmitters of that class in which avariation of contact produces a variation in the strength of current. Inmy transmitter the variable contact to which the transmitting action isdue occurs between two carbon plates or surfaces; and my improvementsconsist, first, in fixing and employing one of the said surfaces as adiaphragm with a clamped edge, while the other, in the form of a carbonplate, rests by its own weight on the said carbon diaphragm; second, 1ndiminishing the surface contact between said diaphragm and plate eitherby shaping them convex and concave,respectively, or by shaping one planeand the other either convex or concave, or by perforating thecontact-surface of the loose plate with numerous small holes to resemblenet-work or a sieve, the object being to facilitate the vibratory actionand yet make contact between as large surfaces as possible. 4

I will now describe my invention by reference to the accompanyingdrawings. Figure 1 shows a cross-section of a transmitter wherein thecontact-surfaces are concave and convex,

respectively. Figs. 2, 3, 4, and 5 show modifications in the form of thecontact-surfaces.

A and B are sections of a case for the contact-surfaces, preferably ofinsulating material, as wood or hard rubber. The section Ais recessed toreceive a metal ring, D, upon which the carbon plate 0 is placed. Thesection of the case B is formed with a ring or flange to enter therecess in A, and when placed in position is firmly fixed by screws a,thus holding, the diaphragm-plate O firmly in its place. The plate E islaid upon 0, so as to be loose or free to move or vibrate. The surfaceof plate 0 is convex, that of plate E is concave, the arc of the latterbeing somewhat greater than that of the former. By this means I attainconsiderable surface contact, and consequently lower resistance with agreater tendency to vibration than with any form yet employed. Thecircuit-terminals y z are connected, respectively, to the plate E andthe metal ring D.

Application filed August 17, 1885. Serial No. 174.609. (No model.)

G'is a mouth-piece, through which vocal utterance is directed upon theplate 0.

In' Fig. 2 the plate 0 is convex and plate E is plane: In Fig. 3 E isconvex and O is plane. In Fig. 4 C is convex and E has three concavitiesof such relative arrangement as to leave a circular rib, which engageswith the fixed plate 0. In Fig. 5 substantially the same end is attainedby perforating the plate E with numerous perforations.

In preparing the plates,I subject them to the heat and vapors of ahydrocarbon-gas retort, as a retort where illuminating-gas ismanufactured. The process is similar to the one described in my PatentNo. 222,652, December 16, 187 9,where carbon buttons or pins are used.The carbon plates so hardened can then be polished to suit therequirements of the transmitter.

I am aware that heretofore a telephone-transmitter has been devisedwherein the variations in resistance were produced by varying thecontact between two flat carbon plates or disks, one of whichrestsloosely upon the other. The operation of such a transmitter,however, is found to be defective and irregular, owing in great part tothe tendency of theplates to stick or adhere together. I have found inpractice that this difficulty may be avoided entirely, and greatimprovements effected in clearness and accuracy of transmission byforming one or both of the disks or plates with a curvedcontact-surface, as above described. I have also found it to be animportant improvement to clamp one of these plates or disks at its edgesand employ it as a diaphragm. This construc tion is very advantageous onaccount of the pure vibration of such a diaphragm.

I am also aware that a transmitter has been heretofore devised having ametal diaphragm and a curved or dished plate of metal resting thereon.Such construction is not includedin my invention ,which, as alreadystated, has special reference to that type of transmitter wherein thevariations in strength of current are produced by varying the degree ofcontact be tween two carbon plates.

What I claim, and desire to secure by Letters Patent, is

1. In a telephone-transmitter, the combina tion of two carbon platesforming the electrodes of a variable contact, one of said plates restingby gravity upon the other, and one having a curved contact-surface,substantially as described.

2. In a batterytransmitter, the combination of two carbon plates havingcurved contactsurfaces, the first of which is fixed in position andforms one electrode of a variable contact, the second of which forms thecomplementary electrode, rests by its gravity upon the first, and isloose and free to vibrate.

3. In a battery-transmitter, the combination of two carbon platesforming the electrodes of a variable contact, the contact-surface of onebeing convex, and that of the other concave.

4:. A batterytransmitter consisting of the combination of two carbonplates having curved contactsnrfaces forming the electrodes of avariable contact, the arc of the concavity of one being greater than thearc of the c011- vcxity of the other.

5. In a telephone-transmitter, the combination of a carbon diaphragm\vitlrfixed edge,

ter, of an inclosingcase intwo sections, one of 0 which is recessed andcontains a metal ring, a carbon plate firmly held in position upon saidring by the second section of the case, and a carbon plate resting uponthe first plate by gravity, but otherwise free to vibrate.

In testimony whereof Ihave signed my name to this specification, in thepresence of two subscribing witnesses, this 14th day of August, 1885.

EMILE BERLINER.

\Vitnesses:

GEO. \VrLLIs PIERCE, THos. D. LOCKWOOD.

